The present invention relates generally to the field of electromagnetic interference and, in particular, to a panel gasket to reduce electromagnetic interference.
Electromagnetic interference (EMI) affects the performance of electrical equipment. A particular electrical circuit may both generate interference and be affected by external interference sources. Low power and low frequency circuits are particularly prone to spurious emissions from EMI. Conversely, high power and high frequency signal sources are typical sources of spurious radiation of EMI.
Reducing undesirable interference, or sensitivity, is largely accomplished by shielding sensitive components. Shielding may take the form of encasing a particular circuit in a metal housing wherein efficiency is maximized by providing a continuous, low impedance electrically conductive housing.
External electrical connections to such a circuit often creates undesirable sources for leakage of EMI. Also, indicator lights, controls and other devices preclude the practical implementation of a complete metal housing surrounding a circuit in many applications.
A typical electrical device includes a number of printed circuit boards equipped with edge connectors. The boards are inserted through an opening in the housing of the electrical device and electrical connections are established by means of edge connectors. The electrical housing is typically of metal construction and, thus, provides a degree of EMI shielding for the inserted electrical printed circuit boards. Indicator lights, such as LEDs, controls, and other connectors may also be attached to the individual circuit boards. Any gaps or openings in the housing creates a possibility of harmful EMI leakage.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a substantially leak-proof, robust gasket to address the problem of undesirable EMI transmissions.
The above mentioned problems associated with electromagnetic interference mitigation, and other problems, are addressed by the present invention and will be understood by reading and studying the following specification.
In particular, an illustrative embodiment of the present invention includes an apparatus for reducing electromagnetic interference, wherein the apparatus includes a cover, a gasket and a supporter. The cover includes a cover face and four cover side walls with each cover side wall substantially normal to the cover face. The cover face and cover side walls form a first cavity. The gasket includes a gasket face and four gasket side walls, each gasket side wall substantially normal to the gasket face and the gasket face and the gasket side walls form a second cavity. The gasket face is adapted to mate with the first cavity. The gasket side walls include a plurality of fingers. Each finger has an end proximate to the gasket face and an end distal to the gasket face, and a middle portion arched in a direction away from the gasket face. The distal end of each finger is aligned substantially normal to the gasket face and the gasket is electrically conductive. The supporter includes a supporter face and four supporter side walls. Each supporter side wall is substantially normal to the supporter face and the supporter face is adapted to mate with the second cavity. Each supporter sidewall includes a slidable engagement portion adapted to receive the distal end of a predetermined number of fingers.
In an alternative embodiment, the cover, gasket and supporter are bonded with spot welds. In one embodiment, for each finger, the proximate end is aligned substantially normal to the gasket surface. In one embodiment, the gasket comprises spring steel. In one embodiment, a mounting tab is connected to the supporter and the mounting tab is adapted for affixation of the apparatus to a printed circuit board. In one embodiment, a handle is connected to the cover and enables manual manipulation of the apparatus. In one embodiment, the apparatus includes a hole in the cover face, gasket face and supporter face and the hole in each of the cover, gasket and supporter is aligned.
In an alternative embodiment, the present invention provides a method of manufacturing an EMI gasket. The method includes providing a cover, forming an electrically conductive gasket, forming a support, coupling the cover to the gasket and coupling the gasket to the support. The cover has a cover face. The gasket defines a cavity and has a plurality of fingers, wherein each finger has a configuration adapted to exert a force in opposition to forces directed toward the cavity. The support slidably engages a portion of each finger and mates with the cavity.
In one embodiment, forming an electrically conductive gasket comprises forming a laser etched gasket. One embodiment includes tempering the gasket. One embodiment includes attaching a planar member to the support. One embodiment provides that coupling the cover to the gasket comprises spot welding. One embodiment provides that coupling the gasket to the support comprises spot welding. One embodiment provides that forming an electrically conductive gasket comprises forming fingers having an arched configuration.
In one embodiment, the present invention provides an apparatus comprising a faceplate, a gasket and an inner support. The faceplate includes a front and a back. The gasket includes a planar surface and a side substantially orthogonal to the planar surface. The planar surface includes a front and a back and the front of the planar surface is coupled to the faceplate back. The side includes a plurality of linear members with each linear member having a trailing end coupled to the planar surface, a leading end distal to the planar surface, and a middle region between the trailing end and the leading end, wherein the gasket is electrically conductive. For each linear member, the middle region is positioned further from the planar surface than the leading end. The inner support is coupled to the planar surface back. The inner support has a side member adapted to slidably engage the leading end of a predetermined number of linear members. The inner support is adapted to oppose deflection of the predetermined number of linear members in a direction parallel to the planar surface.
In one embodiment, the faceplate, gasket, and inner support are substantially rectangular in shape. In one embodiment, the plurality of linear members comprises a first linear member and a second linear member wherein the leading end of the first linear member is coupled to the leading end of the second linear member. In one embodiment, the gasket comprises tempered steel. In one embodiment, the faceplate, the gasket, and the inner support are coupled by a weld. In one embodiment, the apparatus includes a board mounting device coupled to the inner support and the device is adapted to rigidly couple with a board. In one embodiment, the faceplate includes an edge substantially perpendicular to the faceplate and extending in a direction parallel to the plurality of linear members. In one embodiment, each linear member is arched.